The present invention relates to a developer storage unit and an image forming apparatus.
In a conventional image forming apparatus such as a electro-photographic color printer, image forming units corresponding to each color are arranged in a tandem type along a transportation path of a sheet, so that four types of toner are sequentially overlapped and transferred to the sheet, thereby forming a color image.
Each of the image forming units includes a photosensitive drum and a toner image forming unit. The toner image forming unit has a cleaning unit, a charge roller, an exposure unit, and a developing roller arranged round the photosensitive drum. Each of the image forming units further includes a transfer roller arranged to face the photosensitive drum with a transfer belt inbetween, and a toner image transfer unit having a transfer belt cleaning unit.
Further, the image forming apparatus includes a toner discharge portion for transporting unnecessary toner discharged from the toner image transfer unit; a sheet supply tray for supplying the sheet; a transportation roller for transporting the sheet; a fixing unit for fixing the toner image transferred to the sheet; and a discharge tray for placing the sheet with the toner image transferred thereon discharged from an image forming apparatus main body
Further, the image forming apparatus includes a waste toner collection container as a waste toner storage unit detachably attached to the image forming apparatus main body for storing waste toner transported with the toner discharge portion. The waste toner collection container has an opening portion for receiving waste toner transported from the toner discharge portion.
When the waste toner collection container is filled with waste toner, the waste toner collection container is removed, so that the waste toner collection container is replaced with a new one (refer to Patent Reference).    Patent Reference Japanese Patent Publication No. 05-66700
In the conventional waste toner storage unit, when the waste toner collection container is replaced, the waste toner collection container is detached from the image forming apparatus main body, and a lid is attached to the opening portion before discarding the waste toner collection container. Accordingly, when the waste toner collection container is detached from the image forming apparatus main body, waste toner may spill from the opening portion.
Further, the lid to be attached to the opening portion is included in a package of the waste toner collection container. Accordingly, the lid may be lost before attaching the opening portion.
In the view of the problems described above, an object of the present invention is to provide a developer storage unit and an image forming apparatus capable of solving the problems of the conventional waste toner storage unit. In the developer storage unit and the image forming apparatus of the present invention, a closing member is held on the developer storage unit. Accordingly, it is possible to easily and securely close an opening portion without losing the closing member and spilling waste toner from the opening portion when the developer storage unit is replaced.
Further objects and advantages of the invention will be apparent from the following description of the invention.